Silver halide supersensitized photographic emulsion

ABSTRACT

A SILVER HALIDE LIGHT-SENSITIVE PHOTOGRAPHIC EMULSION CONTAINING A COMBINATION OF AT LEAST ONE SENSITIZING DYE REPRESENTED BY THE FOLLOWING FORMULA I AND AT LEAST ONE SENSITIZING DYE REPRESENTED BY THE FOLLOWING FORMULA II:   (-Z1-N(+)(-R1)=)&gt;C-CH=C(-(CH2)2-C6H5)-CH=C&lt;(-Z2-N(-R2)-)   (X1(-))N   WHEREIN R1 AND R2 EACH REPRESENTS A LOWER ALKYL GROUP OR A SUBSTITUTED LOWER ALKYL GROUP, Z1 AND Z2 EACH REPRESENTS AN ATOMIC GROUP NECESSARY TO COMPLETE A BENZOTHIAZOLE NUCLEUS, A BENZONSELENAZOLE NUCLEUS OR A NAPHTHOTHIAZOLE NUCLEUS, X1 REPRESENTS AN ANION, AND N REPRESENTS 0 OR 1, N=0 WHEN AN INTRA-MOLECULAR SALT IS FORMED;   (-Z3-N(+)(-R3)=)&gt;C-CH=C(-R5)-CH=C&lt;(-Z4-N(-R4)-) (X2(-))M   WHEREIN R5 REPRESENTS A LOWER ALKYL GROUP AND R3, R4, Z3, Z4, X2 AND M EACH HAS THE SAME MEANING AS R1, R2, ZI, Z2M X1 AND N RESPECTIVELY.

United States Patent US. Cl. 96-124 7 Claims ABSTRACT OF THE DISCLOSURE A silver halide light-sensitive photographic emulsion containing a combination of at least one sensitizing dye represented by the following Formula I and at least one sensitizing dye represented by the following Formula II:

I l I 1 l )ll 2 wherein R and R each represents a lower alkyl group or a substituted lower alkyl group, Z and Z each represents an atomic group necessary to complete a benzothiazole nucleus, a benzoselenazole nucleus or a naphthothiazole nucleus, X, represents an anion, and n represents 0 or 1, n1=0 when an intra-molecular salt is formed;

wherein R represents a lower alkyl group and R R Z 2,, X and In each has the same meaning as R R Z Z X and n respectively.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a spectrally sensitized silver halide light-sensitive photographic emulsion and especially to a silver halide light-sensitive photographic emulsion in which at least two sensitizing dyes are used in combination, by which a Wavelength region spectrally sensitized by each sensitizing dye is super-sensitized and a high red-sensitivity is obtained.

Description of the prior art In photographic light-sensitive materials commonly used, various spectral sensitivity distributions are required corresponding to the object being photographed. In the photographic light-sensitive material art, a method is well known whereby a certain kind of sensitizing dye is added to the silver halide emulsion to expand its sensitive wavelength range to a further long wavelength range; that is, a spectral sensitization technique.

In general, two or more kinds of sensitizing dyes are used together in the photographic sensitive material in 3,677,765 Patented July 18, 1972 order to obtain a desired spectral sensitivity distribution. However, in many cases, the spectral sensitivity resulting by using two or more sensitizing dyes together, to adjust the spectral sensitivity distribution, is lower than that obtained by using each sensitizing dye by itself. However, in certain cases, the spectral sensitizing fllHCilOll obtained by the use of a sensitizing dye having a limited chemical structure may be additionally strengthened by using it together with another sensitizing dye or organic compound having a certain limited chemical structure. This phenomenon is known as a supersensitization function.

An object of the present invention is to provide a silver halide photographic light-sensitive emulsion having a high red-sensitivity in a spectral sensitized wavelength range of 620-690 nm. by using two different kinds of sensitizing dyes in combination. This wavelength range is a spectral wavelength range used widely in black and white sensitive materials or in color photographic redsensitive layers.

SUMMARY OF 'THE INVENTION The above-mentioned object of the present invention has been attained by using a combination of sensitizing dyes represented by the following Formulae I and II in a photographic silver halide light-sensitive emulsion:

wherein R and R each represents a lower alkyl group (for example, methyl or ethyl, etc.) or a substituted alkyl group commonly used in sensitizing dyes (for example, a 'y-sulfopropyl group, a 'y-sulfobutyl group, a li-sulfobutyl group, a B-hydroxyethyl group, a fi-carboxy propyl group, a e-carboxybutyl group or an allyl group, etc.); 2, and 2;, each represents an atomic group necessary to complete a benzothiazole nucleus, a benzoselenazole nucleus or a naphthothiazole nucleus, wherein the nucleus may be substituted with, for example, a halogen atom (for example, chlorine or bromine, etc.), a lower alkyl group, a hydroxyl group, an alkoxyl group (for example, methoxy or ethoxy, etc.), a phenyl group, a carboxyl group, or an alkoxycarbonyl group (for example, methoxycarbonyl or ethoxycarbonyl, etc.

represents an anion of the type normally used in cyanine dyes (for example, a chlorine, bromine, iodine, p-toluenesulfonic acid or an ethylsulfonic acid ion, etc.); and n=0 or 1, n being 0 when an intra-molecular salt is formed; and

II wherein R represents a lower alkyl group (for example methyl or ethyl, etc.), R and R each represents a lower alkyl group (for example, methyl or ethyl, etc.) or a substituted alkyl group (for example, 'y-sulfopropyl, 'ysulfobutyl, B-sulfobutyl, B-hydroxypropyl, fl-carboxyethyl or allyl, etc.), 2, and Z each represents a group of atoms necessary to form a benzothiazole nucleus, a benzoselenazole nucleus or a naphthothiazole nucleus, wherein the nucleus may be substituted with, for example, a halogen atom (for example, chlorine or bromine, etc.), a lower alkyl group (for example, methyl, ethyl, propyl, etc.) an alkoxy group (for example, methoxy or ethoxy, etc.), an aryl group (for example, phenyl, etc.), a hydroxyl group, a carboxyl group, or an alkoxycarbonyl group (for example, methoxycarbonyl or ethoxycarbonyl, etc.)

represents an anion of the type normally used in cyanine dyes (for example, a chlorine, bromine, iodine, p-toluenesulfonic acid or ethylsulfonic acid ion, etc.); m represents or 1, m being 0 when an intra-molecular salt is formed.

A characteristic of the sensitizing dye represented by Formula I (hereinafter termed sensitizing dye (I) is that the hydrogen atom at the B-position of the methine chain of the cyanine dye containing a benzothiazole nucleus, a benzoselenazole nucleus or a naphthothiazole nucleus is replaced with a phenylethyl group. Such cyanine dyes easily form an optical (color) sensitization range which has a comparatively easy inclination at the long wavelength side of the maximum sensitization part. On the other hand, the cyanine dyes represented by Formula II (hereinafter termed sensitizing dye (l1) easily form an optical (color) sensitization range which has a comparatively steep inclination at the long wavelength side of the maximum sensitization part. A high red-sensitivity can be obtained by using a combination of sensitizing dyes (I) and (II) as compared with the cases of using each sensitizing dye by itself. Further, it is possible to use the dyes together with an optical sensitizer in order to increase the green-sensitivity (a pseudocyanine dye, etc.) or othefl optical sensitizers having other spectral sensitization ranges.

The following compounds are examples of sensitizing dyes which may be used in the present invention. However, the sensitizing dyes shown below are merely given as examples, applicants having no intention of being limited thereto.

r on,

-CH=-C-CH H C1 N I CaHa D3 3- CH2 S (EH2 -on=-on= I OH 01 -IN N 2H0 2)a a' CHaOOC- OH OH The sensitizing dyes represented by Formulae I and II used in the present invention can be produced by any known method.

For example, they can be easily synthesized by those skilled in the art with reference to US. Pat. No. 2,503,776, German patent specification No. 929,080 or German patent specification No. 1,072,765.

Namely, the sensitizing dyes represented by Formula I are prepared by reacting a compound represented by Formula III:

wherein 2,, R X and n have the same meaning as in Formula I, and R represents an alkyl group (for example, methyl or ethyl, etc.), with a compound represented by Formula IV):

The spectral sensitization method of the present invention is elfective for spectrally sensitizing gelatino silver halide protographic emulsions. Further, it is possible to sufliciently sensitize emulsions containing a hydrophilic colloid, excepting gelatin, such as agar-agar collodion, water-soluble cellulose derivatives, polyvinyl alcohol and other synthetic or natural hydrophilic resins by this method.

As the photographic emulsion used in the present invention, mixed silver halide emulsions such as of silver iodo bromide and silver chloroiodo bromide are suitable.

In order to adjust the spectral sensitized photographic emulsion of the present invention, sensitizing dyes (I) and (II) may be admixed with the photographic emulsion by any common method. In practice, coloring material is usually added as a solution in a suitable solvent such as methanol or ethanol to the emulsion. The amount of sensitizing dyes (I) or (H) is preferably within the range of from mole to 10- mole of dye per mole of silver halide.

The molar ratio of sensitizing dye (I) to dye (II) used in the emulsion can vary over a wide range of 9:1-lz9 according to the desired eifect.

The photographic emulsion of the present invention can be subjected to hypersensitization and supersensitization by any well known method. In the preparation of the photographic emulsion of the present invention, additives commonly used such as sensitizers, stabilizers, color controlling agents, hardeners, surface active agents, antifogging agents, plasticizers, development accelerators, color 8 formers or whitening fluorescent agents, etc., can be added to the emulsion by usual methods.

The photographic emulsion of the present invention can be applied to a suitable support such as glass, films of cellulose derivatives, synthetic resin films and baryta paper by any common method.

The following examples further illustrate the present invention.

Silver halide photographic emulsions were prepared by adding the above-mentioned sensitizing dyes (J) and (II) individually to a silver iodide bromide emulsion (AgI:AgBr=7 molesz93 moles) On the other hand, silver halide photographic emulsions which contain a combination of sensitizing dyes (I) and (II) were prepared. After applying these emulsions to triacetyl cellulose film bases and drying, the resulting films were exposed to a 64-lux daylight lamp (corresponding to 5400 K.) as the light source through a Fuji No. 7 filter (trademark) (red filter through which rays having a long Wavelength of about 580 nm. penetrate, produced by Fuji Photo Film Co., Ltd.) and subjected to development. As the developing solution, that having a composition described in Table l was used,

TABLE 1 G. Metol 2 Sodium sulfite Hydroquinone 5 Borax 2 Water to make, 1 liter.

Table 2 shows the red sensitivity and maximum sensitization achieved employing the above-mentioned sensitizing dye (I) by itself. Table 3 shows the red sensitivity and maximum sensitization realized when using the abovementioned sensitizing dye (H) by itself. Table 4 shows the red sensitivity and maximum sensitization realized when using combinations of sensitizing dyes (I) and (II).

TABLE 2 Amount of sensitizing dye (10- molslkg. emulsion) (ml.) Emulsion Maximum sensitization Red tnm.) sensitivity oomocoemoemeeeomoooeoo Red sensitivity is shown as the relative sensitivity based on the red sensitivity of sensitizing dye B being 100 when exposed using Fuji No. 7 filter (red filter).

TABLE?! Amount 0! sensitizing dye (IO- mols/kg Maximum emulsion) sensitization Red Emulsio (mm) sensitivity 8 AgBr/I 664 440 8 AgBr/I 660 294 8 .AgBr/I 632 236 3 AgBr/I 632 141 6 AgBr/I 625 147 8 AgBrII 636 224 8 AgBr/I 670 580 8 AgBr/I 657 253 8 AgBr/I 670 310 6 AgBr/I 690 470 8 AgBr/I 660 400 Red sensitivity is shown as the relative sensitivity based on the red sensitivity of sensitizing dye B bong 100 when exposed using the Fuji No. 7 filter (red filter).

TABLE 4 Amount of Max!- sensitizlng mum dye (10- mols/ sensiti- Red Example kg. emulsion) zation sensio. Dye No (ml) Emulsion (mn.) tivity A 8 AgBr/I 634 206 8 AgBr/I 664 440 1 A 1 6 2 AgBr/I 658 550 B 8 AgBr/I 620 100 4 3 AgBr/I 632 141 2 B 4 5 3 AgBr/I 640 215 C 8 .AgBr/I 625-530 190 9 6 .AgBr/I. e70 310 3 C 9 6 2 AgBr/I 644 380 D 8 AgBr/I 638 153 5 6 AgBr/I 625 147 10 6 AgBr/I 690 470 4 D 5 6 2 AgBr/I 638 190 5' D 10 4 4 AgBrII 684 586 E s AgBr/I e45 224 3 8 AgBr/I 632 236 6 8 AgBr 636 224 6 E 3 2 6 AgBr/I 640-645 330 7 E 6 2 6 AgBr 645 380 G 6 AgBr/I 640 62 2 8 AgBr/I 660 294 8 G 2 2 6 AgBr/I 660 350 J 8 AgBr/I 630 112 9 J 2 4 4 AgBr/I 650 350 L 6 AgBr/I 644 435 10 L 2 4 4 AgBr/I 658 550 H 8 AgBr/I 628 200 I 8 AgBr/I 600 59 7 8 AgBr/I 670 580 H 7 1 7 AgBr/I 662 700 I 7 1 7 AgBr/I 666 770 K 8 AgBr/I 635 210 F 8 AgBr/I 620 196 13 K 2 4 4 AgBr/I 650 355 14 F 2 2 6 AgBr/I 652 500 L 6 AgBr/I 644 435 8 8 .AgBr/I 657 253 11 8 AgBr/I 660 400 15 L 8 7 1 AgBr/I 640 530 16 L 11 3 5 AgBr/I 658 535 M 8 AgBr/I 626 230 2 8 AgBr/I 660 294 17 M 2 4 4 AgBr/I 645 360 Red sensitivity is shown as the relative sensitivity based on the red sensitivity of sensitizing dye B being 100 when exposed using the Fuji No. 7 filter (red filter).

As is clear from Table 4, it is understood that the red sensitivity increases remarkably when using combinations of sensitizing dyes (I) and (II) as compared with the cases of using the sensitizing dyes (I) and (II) by themselves.

What is claimed is:

1. A silver halide light-sensitive photographic emulsion containing a combination of at least one sensitizing dye represented by the following Formula I and at least one sensitizing dye represented by the following Formula II:

wherein R and R each represents a lower alkyl group or a substituted lower alkyl group, Z and Z each represents an atomic group necessary to complete a benzothiazole nucleus, a benzoselenazole nucleus or a naphthothiazole nucleus, X represents an anion, and n represents or 1, n=0 when an intra-molecular salt is formed;

wherein R represents a lower alkyl group and R R Z Z X and m each has the same meaning as R R Z Z X and 11, respectively.

AH, 5H,

H: 5 i3: 5 01 a (4;

COOK

2H5 (CH2)4CO OBI and 4. The silver halide light-sensitive photographic emulsion as claimed in claim 1 wherein sensitizing dye (II) is a compound selected from the group consisting of 5. The silver halide light-sensitive photographic emulsion as claimed in claim 1 further comprising at least one pseudocyanine dye.

6. The silver halide light-sensitive photographic emulsion as claimed in claim 1 wherein the amount of each of said sensitizing dyes varies from 10- mole to 10- mole per mole of silver halide in said emulsion and wherein the molar ratio of dye (I) to dye (II) varies from 9:1 to 1:9.

7. A light-sensitive photographic material comprising a support having coated thereon at least one layer containing the silver halide light-sensitive photographic emulsion as claimed in claim 1.

and

References Cited UNITED STATES PATENTS 2,422,080 6/1947 Collins et al. 96-124 2,533,427 12/1950 Carroll 96124 3,432,303 3/1969 Jones et al. 96124 3,617,293 11/1971 Shiba et al. 96-424 I. TRAVZIS BROWN, Primary Examiner U.S. Cl. X.R.

UNETEED sures PATENT @LFMQE CERTMECATE @EF CRREQTEN ate 3, 677, 765 Dated July 18 1972 In n Yoshivuki Nakazawa et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In The Heading:

The first inventors last name is misspelled. Should read:

--Yoshiyuki Nakazawa.

Signed and sealed this 10th day of July 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Rene Tegtmeyer Acti Commissioner of Patents At-testing Officer USCOMM-DC 60376-P69 w urs. GOVERNMENT PRINTING OFFICE i989 o-aaa-scu.

"ORM PO-105O (10-69) 

